Overheat preventing system of A.C. motor

Claim 1

A system for controlling a motor which drives a fan of a ventilation arrangement having an adjustable vane for regulating wind volume and which operates in one of at least first and second modes of operation, the controlling system comprising: detector means for generating a first signal when the opening of the vane is greater than a first predetermined value and a second signal when the opening of the vane is less than a second predetermined value; means for supplying control power; and first and second circuits connected in parallel across the power supplying means and respectively including first and second switching means responsive to energization by the control power for respectively switching the motor to the first and second modes of operation, the first circuit further including a first contact means which closes when the first switching means is energized, second contact means which opens when the second switching means is energized, third contact means which opens in response to the second signal from the detector means, and fourth contact means which closes in response to the first signal and the first circuit having the first switching means and the first, second, and third contact means arranged in series with the fourth contact means arranged in parallel across the first contact means, the second circuit further including a first contact means which opens when the first switching means is energized, a second contact means which closes when the second switching means is energized, third contact means which opens in response to the first signal, and fourth contact means which closes in response to the second signal and the second circuit having the second switching means and the first, second, and third contact means arranged in series with the fourth contact means arranged in parallel across the second contact means.

Claim 2

A system for controlling a motor which drives a fan of a ventilation arrangement having an adjustable vane for regulating wind volume and which operates in one of at least first and second modes of operation, the controlling system comprising: detector means for generating a first signal when the opening of the vane is greater than a first predetermined value and a second signal when the opening of the vane is less than a second predetermined value; means for supplying control power; and first and second circuits connected in parallel across the power supplying means and respectively including first and second switching means responsive to energization by the control power for respectively switching the motor to the first and second modes of operation, the first circuit further including a first contact means which closes when the first switching means is energized, second contact means which opens when the second switching means is energized, third contact means which opens in response to the second signal from the detector means, and fourth contact means which closes in response to the first signal and the first circuit having the first switching means and the first, second, and third contact means arranged in series with the fourth contact means arranged in parallel across the first contact means, the second circuit further including a first contact means which opens when the first switching means is energized, a second contact means which closes when the second switching means is energized, third contact means which opens in response to the first signal, and fourth contact means which closes in response to the second signal and the second circuit having the second switching means and the first, second, and third contact means arranged in series with the fourth contact means arranged in parallel across the second contact means.